The U.S. District Judge presiding over all federal Mirena IUD lawsuits, which involve similar allegations that the birth control implant caused women to develop a neurological problem known as pseudotumor cerebri, has excluded plaintiffs’ causation experts, which may result in the dismissal of the litigation.

The conditions involve a buildup of fluid around the brain, which plaintiffs allege is caused by the hormone levonorgestrel released by the IUD, which may cause women to suffer severe headaches, vision problems and other complications.

Given common questions of fact and law raised in complaints filed in U.S. District Courts nationwide, the litigation has been centralized before U.S. District Judge Paul A. Engelmayer for coordinated discovery and pretrial proceedings, as part of a federal MDL, or multidistrict litigation.

As part of pretrial schedule for a series of “bellwether” cases, Judge Englemayer recently considered challenges filed by each side to the admissibility of expert testimony on the issue of general causation, about the alleged link between Mirena and PTC/IIH, and whether levonorgestrel contained in the IUD is capable of causing the condition.

In a 156-page opinion and order (PDF) issued on October 24, Judge Englemayer determined that seven expert witnesses put forward by the plaintiffs should be excluded from testifying, indicating that they were either unqualified or that the rationale of their opinions was unreliable. The decision leaves plaintiffs without evidence to establish causation, and will likely result in dismissal of claims, pending appeal.

Judge Englemayer determined that the risk factors for PTC/IIH include woman of child-bearing age, and being overweight, noting that the Mirena IUD, by definition, is implanted among women of child-bearing age, and that data indicates it is predominantly used by women who are overweight. He also indicated that the decision was influenced by the lack of any findings by medical organizations, regulatory agencies or peer-reviewed literature that the Mirena IUD is a cause of PTC/IIH.

As a result of the order, the Court has directed attorneys involved in the cases to meet and confer about the next steps in the litigation, and whether the MDL should proceed to motions for summary judgement at this time, limited to the issue of general causation. The parties have been directed to submit a joint letter outlining the proposed next steps by November 9.

Mirena is a small, T-shaped device that is placed into the uterus to provide protection against pregnancy for up to five years. Known as an intrauterine device (IUD) or intrauterine system (IUS), the polyethylene frame for Mirena contains a steroid reservoir that release levonorgestrel, which is a second generation progestin used in many forms of birth control.

While other forms of birth control that involve levonorgestrel contain warnings about a risk of pseudotumor cerebri (PTC), plaintiffs alleged that the Mirena warnings have failed to adequately alert women and physicians about risk that the birth control implant may cause a buildup of fluid pressure around the brain. Prompt diagnosis and treatment of the intracranial hypertension from Mirena is critical to avoid permanent damage to the optic nerve.

Prior litigation over migration and perforation injuries associated with the Mirena IUD resulted summary judgment in 2016, after the judge presiding over the cases similarly excluded testimony of several expert witnesses proposed by plaintiffs. While that decision was being appealed, an agreement to settle the Mirena IUD claims was reached in most cases.